Laminated glass comprising pressure-sensitive adhesive

ABSTRACT

A laminated glazing includes a first glass sheet; at least one interlayer sheet made of thermoplastic polymer; optionally a solar-protection sheet or functional metal layer having reflective properties in the infrared region and/or in the solar radiation region; and at least one sheet of pressure-sensitive adhesive, in direct contact with a heat-sensitive functional sheet; a second glass sheet; the first glass sheet being in direct contact with the interlayer sheet; the second glass sheet being in direct contact with the sheet of pressure-sensitive adhesive.

The invention relates to a laminated glazing comprising a stack of thin layers, including (i) at least two glass substrates assembled together by (ii) at least one interlayer of organic nature and (iii) at least one heat-sensitive functional layer combined with the internal face of one of said glass substrates by (iv) a layer of pressure-sensitive adhesive. Advantageously, this glazing is electrically switchable.

The invention also relates to the use of such a glazing to manufacture a glazing intended to equip a vehicle, in particular chosen from a motor vehicle, a bus, a truck, a boat, an aircraft, such as a plane or a helicopter, and a train.

The two glass substrates of said glazing are optionally held together by a frame structure. The laminated glazing of the invention can thus be a vehicle glazing chosen from a windshield, a front side glazing, a rear side glazing, a rear window and a roof glazing. Advantageously, it is a roof glazing.

The interlayers are provided in the form of films. These are generally films made of polyvinyl butyral, abbreviated to PVB, or ethyl/vinyl acetate, abbreviated to EVA. PVB has the advantage of exhibiting a good adhesion to glass and a high degree of elongation before tearing.

The laminated glazing comprising such a plastic interlayer thus proves to be impact-resistant. During impact with a foreign body, the glass crazes and the fracture remains localized at the point of impact without detrimental effect in the visibility through the glazing. In addition, the PVB interlayer keeps the pieces of glass in place, which reduces the risk of being cut by glass splinters and makes it possible to retain the leaktightness of the glazing. Finally, the residual energy of the body is absorbed by this interlayer. The glazing thus prevents the body from passing through, if the impact is not disproportionate.

The main stages of the process for the manufacture of a laminated glazing are as follows:

-   -   Washing the glass: The glass substrate is cut out beforehand and         optionally shaped. In order to remove any traces of         contamination, the glass is washed with ionized water and         carefully dried.     -   Assembling: It is carried out in a dust free closed chamber at a         temperature of 18-20° C. and with a relative humidity of the         atmosphere of 30%. The layers of glass and of interlayer are         superposed as a function of the desired composition. The         trimming of the laminated volume is carried out before entering         the preheated oven.     -   Degassing: This is the most critical operation. It is a matter         of removing the air trapped, in the form of possible air         bubbles, between the interlayer and the glass sheet and of         sealing the edges of the assembly so as to prevent any risk of         penetration of air during the final autoclaving operation. This         operation is carried out by double calendering with a preheating         oven at approximately 60° C. The temperature conditions are a         function of the type of assembly and of the speed of the line.     -   Autoclaving: The definitive adhesive bonding of the glass and         the interlayer is carried out in an autoclave at a high pressure         and with a rise in temperature in order to ensure strong bonding         of the assembly.

Thus, for an interlayer made of PVB, the operation is carried out at a pressure between 10 and 12 bar, limits included, and at a temperature of 120 to 145° C., limits included. This makes it possible to sufficiently creep the PVB to perfectly match the surface of the glass and create adhesion.

For an interlayer made of EVA, the adhesive bonding is carried out at a temperature slightly below 100° C. The cycle times are a function of the filling and of the composition of the laminated glazing.

-   -   Cleaning: A second peripheral trimming is necessary in order to         remove the excess interlayer, due to the creep.

However, in the case where it is desired to manufacture a laminated glazing comprising functional intermediate layers, the temperature at which the adhesive bonding has to take place can present a problem. The adhesive bonding of the interlayer film or films of the glazing during the lamination phase has to take place, very often, at a temperature which is difficult to render compatible with the use of other layers, in particular of “functional” layers, which are sensitive to the temperature. This is because many functional coatings experience permanent damage to their function by the exposure to such autoclaving temperatures.

Currently, in order to manufacture such a laminated glazing in just one hot lamination stage, without causing a loss of functionality to the functional layer, an interlayer made of EVA is used in place of PVB, the EVA exhibiting a processing temperature or adhesive bonding temperature for carrying out the lamination which is much lower than that of PVB.

However, the PVB layer remains essential due to its impact strength in numerous applications. It is thus impossible to carry out the manufacture of a laminated glazing exhibiting a heat-sensitive functional coating with just one high-temperature lamination stage.

The result of this is a two-step lamination process developed by Saint-Gobain. In this process, which forms part of the prior art, (i) a PVB layer is, during a first hot lamination stage, applied at a temperature which can reach 120° C. to a glass sheet intended to form the side of the glazing in contact with the exterior space of the vehicle, then the assembly can be combined, for example with other sheets, such as a metal sheet, which offer additional functionalities, and finally (ii) an active film, for example a film for a suspended particle device, abbreviated to SPD, is added in a second hot lamination stage at a temperature of less than 100° C., said film being rendered integral by EVA with the glass layer intended to form the side of the glazing in contact with the interior space of the vehicle and with the laminate comprising the PVB of the preceding stage. In this way, the SPD film is never exposed to the high lamination temperature required for the processing of the PVB.

Only a process including at least two hot lamination stages is thus currently possible for the lamination of a laminated glazing comprising at least one layer of PVB and of SPD. However, this process requires several handling operations, cannot be carried out continuously and thus consumes time and energy.

The aim of the invention is to succeed in overcoming the disadvantages of the prior art by developing a novel type of laminated glazing stack, the layers of which adhere effectively to one another, while reconciling a sensitization to heat and an impact strength.

Another important aim of the invention is to provide a process for the manufacture of such a stack and, by extension, of a laminated glazing comprising such a stack which is economically advantageous.

The applicant company has developed an impact-resistant laminated glazing exhibiting at least one heat-sensitive active film which can now be produced in a single hot lamination stage employing at least one polymeric interlayer.

A subject matter of the invention is thus a laminated glazing comprising:

-   -   a first glass sheet 1;     -   at least one interlayer sheet 3 made of thermoplastic polymer;     -   optionally a “solar-protection” sheet 4 or functional metal         layer having reflective properties in the infrared region and/or         in the solar radiation region;     -   at least one sheet of pressure-sensitive adhesive 5, in direct         contact with a heat-sensitive functional sheet 6;     -   a second glass sheet 2;         said first glass sheet 1 being in direct contact with said         interlayer sheet 3;         said second glass sheet 2 being in direct contact with said         sheet of pressure-sensitive adhesive 5.

The sheet of pressure-sensitive adhesive 5 and the second glass sheet 2 are in direct contact at the internal face of this second glass sheet 2.

The two faces of one and the same glazing are each in contact with an external medium. These external media are each distributed on either side of said glazing.

Within the meaning of the invention, the “external” face of a layer or of a sheet means the face of said layer or of said sheet of the glazing closest to the closest external medium.

Within the meaning of the invention, the “internal” face of a layer or of a sheet means the face of said layer or of said sheet of the glazing furthest from the closest external medium.

Within the meaning of the invention, the terms “sheet”, “film” or “layer” will be used without distinction in the present invention to define the different strata of the structure of the laminated glazing according to the invention. These terms have the same meaning here.

Advantageously, the first glass sheet 1 of said glazing is in direct contact with the external medium of the latter, which is the medium external to the vehicle having such a laminated glazing which is a subject matter of the invention. Respectively, the second glass sheet 2 of said glazing is in direct contact with the external medium of the latter which proves to be the medium internal to the vehicle, that is to say the medium where the driver and the possible passengers are found.

According to a first embodiment of the invention represented in FIG. 1, the laminated glazing according to the invention successively comprises:

-   -   a first glass sheet 1,     -   an interlayer sheet 3 made of thermoplastic polymer,     -   optionally a “solar-protection” sheet 4 or functional metal         layer having reflective properties in the infrared region and/or         in the solar radiation region,     -   a first sheet of pressure-sensitive adhesive 5,     -   a heat-sensitive functional sheet 6,     -   a second sheet of pressure-sensitive adhesive 5,     -   a second glass sheet 2.

According to the invention, the thermoplastic polymer of the interlayer sheet 3 is advantageously chosen from polyvinyl butyral, polyurethane, ethylene/vinyl acetate and ionomers.

According to the invention, the thermoplastic polymer of the interlayer sheet 3 is advantageously PVB.

According to the invention, the pressure-sensitive adhesive is advantageously chosen from pressure-sensitive adhesives based on acrylates and pressure-sensitive adhesives based on silicone.

According to the invention, the heat-sensitive functional sheet 6 is advantageously based on encapsulated liquid crystals, on electrophoretic particles dispersed in the medium, on particles dispersed in an electrophoretic fluid or on particles for the polarization of light.

According to the invention, the “solar-protection” sheet is advantageously made of silver or any other metal having light-reflecting properties or a metal or metal compound having light-absorbing properties. According to the invention, the laminated glazing is flat or bent.

In addition, it is advantageously a vehicle glazing chosen from a windshield, a front side glazing, a rear side glazing, a rear window and a roof glazing.

It is advantageously a glazing for a vehicle chosen from a motor vehicle, a train, a truck, a plane and a bus.

Another subject matter of the invention is a process for the manufacture of a laminated glazing as defined above, in which the stages of installing the different sheets take place starting (i) from the installing of the interlayer sheet 3 made of thermoplastic polymer on the internal face of the first glass sheet 1, or starting (ii) from the installing of the second sheet of pressure-sensitive adhesive 5 on the internal face of the second glass sheet 2, or starting (iii) from the installing of a sheet of pressure-sensitive adhesive 5 on at least one of the two faces of a heat-sensitive functional sheet 6.

The process for the manufacture of a laminated glazing according to the invention comprises:

-   -   at least one stage of installing an interlayer sheet 3 made of         thermoplastic polymer on the internal face of a first glass         sheet 1, optionally bent beforehand, and optionally the         installation of a “solar-protection” sheet 4 on the face which         has remained vacant of said interlayer sheet 3, which is thus         sandwiched between said first glass sheet 1 and said optional         “solar-protection” sheet 4, so as to form a first partial         laminate 7, and/or     -   at least one stage of installing a first and/or a second sheet         of pressure-sensitive adhesive 5 on at least one of the two         faces of a heat-sensitive functional sheet 6.

The embodiments described below made it possible in particular to obtain the stacks according to the invention as represented in FIG. 1.

According to the invention, the first sheet of pressure-sensitive adhesive 5 is positioned on the first face of the heat-sensitive functional sheet 6 and the second sheet of pressure-sensitive adhesive 5 is positioned on the second face of said heat-sensitive functional sheet 6 which has remained vacant, so as to obtain a second partial laminate 8.

According to a first embodiment of the process according to the invention, the second partial laminate 8 is applied via one of its faces which are pressure-sensitive adhesives 5 on or under the first partial laminate 7, either directly on the vacant face of the sheet of thermoplastic polymer 3 of the latter or optionally on the vacant face of the “solar-protection” sheet 4, when the latter is present, of this first partial laminate 7, and the second glass sheet 2, optionally bent beforehand, is applied at its internal face on or under the face of the resulting laminate, opposite the face which has remained vacant of the first glass sheet 1.

According to a second embodiment of the process according to the invention, the second glass sheet 2, optionally bent beforehand, is applied at its internal face on or under one of the faces of said second partial laminate 8, so as to form a third partial laminate 9.

Said third partial laminate 9 can subsequently be installed via its face which is a pressure-sensitive adhesive 5 on or under the first partial laminate 7, either directly on the vacant face of its sheet of thermoplastic polymer 3 or optionally on the vacant face of its “solar-protection” sheet 4, when the latter is present.

According to the invention, the process for the manufacture of the laminated glazing can comprise, in addition, at least:

-   -   a stage of degassing the resulting laminate under vacuum, with         use of a peripheral seal or of a vacuum bag,     -   optionally one stage of heat sealing of the edges of said         laminate, and     -   one autoclaving stage.

The process can additionally comprise at least one calendering stage, optionally one hot calendering stage.

The invention also relates to the use of a glazing as defined above to manufacture a vehicle glazing chosen from a windshield, a front side glazing, a rear side glazing, a rear window and a roof glazing and/or to manufacture a glazing for a vehicle chosen from a motor vehicle, a train, a truck, an aircraft and a bus.

The glass substrate of the laminated glazing according to the invention can be of the type sold under the Planiclear® or Planitherm® trade name by Saint-Gobain, indeed even VG10. Its thickness will be chosen as a function of the use envisaged.

The laminated glazing according to the invention comprises at least one sheet of pressure-sensitive adhesive.

A pressure-sensitive adhesive, abbreviated to PSA and commonly called self-adhesive, is an adhesive which forms a bond when a pressure is applied to it so as to render the adhesive integral with a surface to be adhesively bonded. Neither solvent nor water nor heat is necessary to activate the adhesive. It is used in motor vehicle trims and in a great variety of other products.

As indicated by its name of “pressure-sensitive”, the degree of bonding between a given surface and the self-adhesive binder is influenced by the amount of pressure used to apply the adhesive to the target surface. Other factors are also involved and are important for good adhesion, such as softness, surface energy and removal of contaminants.

PSAs are generally designed to form a bond and to maintain the latter at ambient temperature. A person skilled in the art will take care to choose a self-adhesive adhesive formulation suited to the conditions of its use. This is because PSAs generally experience a reduction in or disappearance of their adhesion at low temperature and experience a reduction in their ability to withstand shearing at elevated temperatures.

PSAs are generally based on an elastomer coupled with an appropriate additional adhesive agent or “tackifying” agent (for example an ester resin).

The elastomers can be based:

1/ on acrylates, which may be sufficiently sticky not to require an additional tackifying agent,

2/ on nitrites,

3/ on silicone, requiring special tackifying agents, such as silicate resins of “MQ” type composed of monofunctional trimethylsilane (“M”) which has reacted with quadrifunctional silicon tetrachloride (“Q”). PSAs based on silicone are, for example, polydimethylsiloxane gums and resins dispersed in xylene or a mixture of xylene and toluene,

4/ on block copolymers based on styrene, such as styrene-butadiene-styrene (SBS), styrene-ethylene/butylene-styrene (SEBS), styrene-ethylene/propylene (SEP) or styrene-isoprene-styrene (SIS) block copolymers,

5/ on vinyl ethers.

Advantageously, the pressure-sensitive adhesive in accordance with the invention is chosen from PSAs based on acrylates and PSAs based on silicone.

These adhesives are sold in the form of double sided adhesive rolls.

Mention may be made, as PSAs based on silicone, of the Dow Corning® adhesives, such as 2013 Adhesive, 7657 Adhesive, Q2-7735 Adhesive, Q2-7406 Adhesive, Q2-7566 Adhesive, 7355 Adhesive, 7358 Adhesive, 280A Adhesive, 282 Adhesive, 7651 Adhesive, 7652 Adhesive or 7356 Adhesive.

The laminated glazing also comprises, in addition, a heat-sensitive functional sheet.

It can be a suspended particle device (SPD) film or a laminate of such a film, in which the film comprises substrates coated, on a portion at least of their internal surface, (i) with a conductive polymer, such as, for example, polythiophene, or (ii) with an inorganic conductive layer, such as, for example, indium tin oxide, in order to act as electrode means. The polymer can be applied in the form of an aqueous composition comprising, in addition to the polymer, at least one solvent and at least one binder. A preferred conductive polymer based on polythiophene is a polyethylenedioxythiophene (PEDT) polymer. The polymer can be doped with polystyrenesulfonate. The polymer electrodes can be connected to a conductive material which extends beyond an external limit of the film to connect the film to an appropriate voltage source.

Mention may also be made of the films which comprise a polymer matrix and exhibit droplets of a liquid light modulator suspension containing a plurality of particles dispersed in a liquid medium in suspension distributed within the matrix. Said medium in suspension (a) is virtually immiscible with the polymer matrix, (b) has, at atmospheric pressure, a boiling point greater than approximately 100° C., (c) has an electrical resistivity of at least approximately 0.8×10⁶ ohms per square and (d) has a refractive index at 25° C. which differs by not more than approximately 0.002 from that of the polymer matrix, measured at virtually the same temperature. The suspension medium includes at least one liquid compound selected from the group encompassing methylpyrrolidinone, ethylpyrrolidinone, dimethyl malonate, diethyl malonate, dimethyl succinate, di(propylene glycol) methyl ether, dimethylphthalate, butyl phthalyl butyl glycolate, ethyl lactate, propylene carbonate, dimethyl perfluorosuberate, dimethyl tetrafluorosuccinate, tetra(ethylene glycol) dimethyl ether, tri(ethylene glycol) dimethyl ether, di(ethylene glycol) dimethyl ether, ethylene glycol phenyl ether, epoxidized linseed oil, epoxidized soybean oil, diethyl isophthalate, a laurate ester based on silicone copolyol, a copolymer of silicone copolyol, an ester of silicone copolyol, an isostearate ester based on silicone copolyol, a pelargonate ester based on silicone copolyol, dimethyl octofluoroadipate and also corresponding mixtures and, optionally, at least one previously known liquid suspension medium. The polymer matrix can optionally be crosslinked to form the film in order to produce a crosslinked polymer matrix.

Such a film comprising a suspended particle device is appropriate for being used as light modulator of a laminated glazing according to the invention.

It can also optionally be a film containing encapsulated particles dispersed in a suspension or electrophoretic fluid. Said fluid can be a mixture of two or more than two fluids or else a single fluid. Furthermore, these particles can themselves contain a liquid and be dispersed in a suspension fluid. In any case, the suspension fluid can have a density or a refractive index, the values of which are substantially suited to those which characterize the particles dispersed in the fluid. They can in particular be colored polymer particles preferably having a surface functionality of retention of the charges. In electrophoretic media, it is advantageous to use pigment particles comprising polymer shells comprising from 0.1 to 5 percent in moles of repeat units resulting from a fluorinated acrylate monomer or from a fluorinated methacrylate monomer. The polymer specifically has a branched-chain structure, with side chains which extend from a main chain.

The conductor fluid can be colored. It can comprise a polar solvent and a colorant chosen from a pigment and/or a dye. The colored conductor fluid should not cause electrical failure of a dielectric in the device in which it is employed. An agent for controlling electrical conductivity can optionally be added to the colored conductor fluid.

The application of electric fields in a glazing, provided with such a film, by electrophoresis makes it possible to influence the optical properties of said glazing.

In addition, the glazing can be a glazing having available an electrochromic system comprising electrically conductive layers, separated by a layer of an electrochromic material, an electrolyte and a counterelectrode, said electrically conductive layers each being provided with an electrically conductive strip made of a material having an electrical conductivity which is high with respect to that of the electrically conductive layers, the electrically conductive strips being positioned along opposite edges of the glazing and being connected to a voltage generator which applies, in the coloration phase (or respectively in the decoloration phase), a difference in potential between two points A and B respectively belonging to the electrically conductive layers and in the immediate vicinity of the electrically conductive strips. Advantageously, the electrically conductive strips are made of copper and are welded to the conductive electrode as defined above, the layer of an electrochromic material consists of a cathodic electrochromic material, such as, for example, tungsten trioxide, the counterelectrode consists of an anodic electrochromic material, such as, for example, iridium oxide, and/or the electrolyte is a proton conducting electrolyte, such as, for example, a polymeric complex of polyethylene oxide and orthophosphoric acid which is anhydrous, or a lithium ion or proton (H⁺) conducting electrolyte.

Mention may thus be made, for example, of viologens and conductive polymers, such as polyaniline or PAni.

Finally, mention also be made of functional films based on liquid crystals dispersed in a polymer matrix known under the abbreviated acronym PDLCs. Liquid crystals dispersed in a polymer matrix are a category of heterogeneous materials consisting of a dispersion of microdroplets of liquid crystals in a solid and more or less flexible polymer matrix. These materials exhibit electrooptical properties. This is because they can switch between a highly diffusive opaque state (OFF state) and a transparent state (ON state) after application of an electric field.

The PDLC system is employed in switchable windows. It has several advantages, such as ease of manufacture, ease of use on a large scale, stability, speed of their response time and the fact of not requiring the use of polarizers which absorb almost half the incident light.

Different mesophases can be used to prepare these materials: the nematic phase, the cholesteric phase and the A and C* smectic phases.

The principle of the electrooptical systems using a PDLC consists of a composite sandwiched between two electrodes consisting of glass plates, one face of which is covered with a transparent conductive layer of indium tin oxide (ITO). In the absence of an electric field, the mean orientation of the liquid crystal molecular directors in the liquid crystal is random. The difference in refractive index between the segregated liquid crystal and the macromolecular matrix results in a material having a milky and opaque appearance which will scatter light (OFF state).

During the application of an electric field between the electrodes of the cell, the molecular directors become oriented in the direction of the field. A beam of normal index passes through the droplets with a refractive index equal to n0, the ordinary index of liquid crystal molecules. If this index is close to that of the polymer matrix, the film appears clear and transparent (ON state).

Compared with standard laminated glazings, the electrically switchable glazing provides specific additional functions which are reflected in terms of user comfort, light transmission and energy savings. The switchable glazing can rarely be installed directly as a finished product. Typically, before use of the switchable glazing, a prelamination is necessary. For example, for use of an SPD film in the context of the sunroof of a motor vehicle, it is necessary to produce a laminate between at least 2 sheets of clear or tinted glass and PVB. This is done in order to meet the safety standards in the event of the glass breaking and to extend the lifetime of the SPD film.

The laminated glazing according to the invention additionally comprises at least one polymeric interlayer sheet. The interlayer is made of organic polymer. This polymer can in particular be made of polyvinyl butyral, abbreviated to PVB, of ethylene/vinyl acetate, abbreviated to EVA, or of polyurethane or be based on ionomers. Mention may be made, as examples of ionomers, of the Sentryglass® products sold by DuPont®. Advantageously, PVB is concerned.

The laminated glazing according to the invention can optionally comprise, finally, a “solar-protection” sheet, also known as solar control sheet.

A type of stack of layers which is known to confer “solar-protection” properties on the substrates comprises (i) at least one functional metal layer having properties of reflection in an infrared region and/or in the solar radiation region, in particular a functional metal layer based on silver or on silver-containing metal alloy, and/or a functional layer having properties of absorption in the solar radiation region and/or in the infrared region.

Solar radiation is composed of ultraviolet radiation and of visible light. In this type of stack, the functional layer is thus positioned between two dielectric coatings each comprising at least one dielectric layer which are each made of a dielectric material of the nitride or oxide type. Mention may be made, for example, of silicon, aluminum, Nb, Ti, InSn and SnZn nitrides and oxides.

Mention may preferably be made of silicon nitride, niobium oxide and titanium oxide.

Mention may be made, as examples of solar control film, of the Solargard® reflective products from Saint-Gobain, such as LX70, and the Ceramic Series absorbing products from Huper Optik®, such as Huper Optik® C5. From the optical viewpoint, the aim of these coatings, which frame the functional metal layer, is “to render antireflective” this functional metal layer.

“Coating” within the meaning of the present invention should be understood as meaning that there may be just one layer or several layers of different materials inside the coating.

As a reminder, the solar factor of a glazing is the ratio of the total solar energy entering the premises through this glazing to the total incident solar energy, and the selectivity S corresponds to the ratio of the light transmission T_(Lvis) in the visible region of the glazing to the solar factor FS of the glazing and is such that: S=T_(Lvis)/FS.

Furthermore, these glazings can be incorporated in glazings exhibiting specific functionalities, such as, for example, heated glazings.

As usual, “dielectric layer” within the meaning of the present invention should be understood as meaning that, from the viewpoint of its nature, the material is “nonmetallic”, that is to say is not a metal. In the context of the invention, this term denotes a material exhibiting an n/k ratio over the entire wavelength range of the visible region (from 380 nm to 780 nm) which is equal to or greater than 5. It is known to a person skilled in the art that n is the refractive index and k is a constant specific to a given medium characterizing a material.

The physical thickness of said functional metal layer is preferably between 5 nm and 20 nm, including these values, in order to achieve an emissivity <2.5%.

In another specific version of the invention, said dielectric coating positioned or located between the face of the substrate and said functional metal layer comprises a layer having a high refractive index made of a material exhibiting a refractive index of between 2.3 and 2.7, this layer preferably being based on oxide. The refractive index values indicated in the present document are the values measured as usual at the wavelength of 550 nm.

This high-index layer preferably exhibits a physical thickness of between 5 and 15 nm.

This high-index layer makes it possible to maximize the high light transmission in the visible region of the stack and has a favorable effect on neutral colors being obtained, both in transmission and in reflection.

The physical thickness of said dielectric layer based on Nb oxide and/or on Ti oxide nitrite is preferably between 10 and 60 nm.

In another specific version of the invention, the functional metal layer is deposited directly on an underblocker coating positioned between the functional metal layer and the dielectric coating underlying the functional layer and/or the functional layer is deposited directly under an overblocker coating positioned between the functional metal layer and the dielectric coating overlying said functional metal layer and the underblocker coating and/or the overblocker coating comprises a thin layer (i) based on metal chosen from nickel, titanium, chromium, gold, copper and their alloys and (ii) exhibiting a physical thickness t′ such that 0.2 nm≤t′≤2.5 nm. Mention may be made, as alloy, of NiCr.

In another specific version of the invention, the final layer of the overlying dielectric coating, the one furthest from the substrate, is based on oxide, preferably deposited substoichiometrically, and in particular is based on titanium oxide (TiO_(x)) or based on mixed zinc tin oxide (SnZnO_(x)).

The substrates of the glazing according to the invention are capable of undergoing a heat treatment without damage for the stack of thin layers. They are thus optionally bent and/or tempered.

The details and advantageous characteristics of the invention emerge from the following examples 1 and 2, which are nonlimiting. The numbers of the laminates refer to FIG. 1.

EXAMPLE 1

Example 1 was carried out in the following way.

1/ Preparation of Partial Laminate 7

A transparent substrate of glass type is assembled with a standard PVB sheet on which is applied a solar control film, so as to obtain a partial laminate 7. The PVB film can be clear or tinted, as long as it responds to the safety demands required for the intended use.

The partial laminate 7 prepared above is placed in a bag which is leaktight, except at one of the sides of said bag. The bag is subsequently placed in a vacuum chamber and a vacuum is created in said bag, over a period of time of approximately 30 min, as a function of the power of the machine. The bag is sealed under vacuum and is subsequently placed in an autoclave with a prescribed heating cycle, namely 120° C. under 10 bar, in order to carry out the lamination targeted. If the application envisaged does not require the use of a solar control film, the latter can be replaced with a dummy film with a low surface energy, for example a film of ethylene/tetrafluoroethylene (abbreviated to ETFE), which can be easily detached from the surface of the PVB after lamination prior to the combining of the resulting laminate with another surface. Reference is then made to “false lamination”.

2/ Preparation of a Partial Laminate 8

Another partial laminate, namely a partial laminate 8, is prepared using two films of precoated PSA. Each of the films is positioned between two protective films.

A person skilled in the art can easily carry out an R2R process, where a heat-sensitive film is simultaneously introduced between two PSA films, forming a sandwich with a PSA film on each side of said heat-sensitive film. For this, one of two protective films of each of the PSA films is removed and each PSA face thus released is respectively applied to one of the two faces of the heat-sensitive film. The three films (the two PSA films and the heat-sensitive film) are subsequently pressed together in a pressure pinch region at ambient temperature.

3/ Preparation of a Partial Laminate 9

A second transparent substrate of glass type is introduced into a pressing slit. Depending on the adhesive used and on the heat and according to the final use required, the partial laminate 8 can be applied to the second glass substrate so as to match said partial laminate 8 to the curvature of the pane. In any case, the application of one of the two PSA films, freed from its protective film, terminates the assembling of the partial laminate 9 resulting from the assembling of the partial laminate 8 with the second glass sheet.

4/ Assembling of the Partial Laminate 9 with the Partial Laminate 7

The final assembling giving rise to the formation of the assembly of the laminated system represented in FIG. 1 is carried out by combining together the partial laminates 9 and 7. This combining takes place by virtue of the removal of the final protective film from the PSA layer, still vacant, of the partial laminate 9 and by bringing the PSA film of the partial laminate 9 into contact with the solar control film of the partial laminate 7 and by pressing the laminates 9 and 7 together against one another at this contact region in order to cause the partial laminate 9 to adhere to the partial laminate 7.

The nature and the thickness of the layers and also the conditions for deposition of said layers of example 1 above and of example 2 below are shown in the following table 1:

TABLE 1 Layer Deposition (No. according pressure/ to FIG. 1) Material employed temperature Thickness* Glass substrate Planiclear ® or   2 mm (1, 2) Planitherm ® or VG10 (tinted glass) Interlayer Standard PVB, clear 10 Mbar 0.76 mm (3) or tinted at 120° C. Solar control X70 from Thin multilayer layer Solargard ® or structure with a (4) XIR70 from thickness <250 nm Southwall ® deposited on a 25 or or HuperOptik C5 50 μm PET layer Adhesive layer Aeroset ® PSA Wet coating with a (5) from Ashland thickness of approximately 2 μm Heat-sensitive SPD from  0.5 mm functional layer Hitachi ® (6) *geometrical or physical thicknesses (and not the optical thicknesses)

EXAMPLE 2

In an alternative form, the partial laminates 7 and 8, the obtaining and the preparation of which are described above, are preassembled in a first step. This combining takes place by virtue of the removal of the final protective film from the PSA layer, still vacant, of the partial laminate 8 and by bringing the PSA film of the partial laminate 8 into contact with the solar control film of the partial laminate 7 and by pressing the laminates 8 and 7 together against one another at this contact region in order to cause the partial laminate 8 to adhere to the partial laminate 7.

The resulting laminate, itself freed from the final protective film of its PSA layer, still vacant, is applied to a second glass substrate. The adhesion of the second glass substrate to the laminate resulting from the combining of the partial laminates 7 and 8 is obtained by simple pressing of the combined assembly.

The force of pressure during the pressing stages of examples 1 and 2 is adjusted by a person skilled in the art as a function of the materials used in order not to damage the integrity of the layers or films

It is possible, with the invention, to manufacture a laminated glazing comprising at least one PVB layer and at least one heat-sensitive functional layer in a single stage of lamination by autoclaving.

The use of a PSA layer simplifies the manufacture and reduces the cost with respect to the use of EVA.

In addition, the mechanical strength of the stack according to the invention is very good. Furthermore, the general chemical behavior of this stack is good overall.

The present invention is described in that which precedes by way of example. It is understood that a person skilled in the art is in a position to carry out different alternative forms of the invention without, however, departing from the scope of the patent as defined by the claims. 

1. A laminated glazing comprising: a first glass sheet; at least one interlayer sheet made of thermoplastic polymer; optionally a solar-protection sheet or functional metal layer having reflective properties in the infrared region and/or in the solar radiation region; at least one sheet of pressure-sensitive adhesive, in direct contact with a heat-sensitive functional sheet; a second glass sheet; said first glass sheet being in direct contact with said interlayer sheet, said second glass sheet being in direct contact with said sheet of pressure-sensitive adhesive, and said sheet of pressure-sensitive adhesive and said second glass sheet being in direct contact at the internal face of this second glass sheet.
 2. The laminated glazing as claimed in claim 1, successively comprising: the first glass sheet, the interlayer sheet made of thermoplastic polymer, optionally the solar-protection sheet or functional metal layer having reflective properties in the infrared region and/or in the solar radiation region, the first sheet of pressure-sensitive adhesive, the heat-sensitive functional sheet, the second sheet of pressure-sensitive adhesive, the second glass sheet.
 3. The laminated glazing as claimed in claim 1, wherein the thermoplastic polymer of the interlayer sheet is chosen from polyvinyl butyral, polyurethane, ethylene/vinyl acetate and ionomers.
 4. The glazing as claimed in claim 1, wherein the thermoplastic polymer of the interlayer sheet is PVB.
 5. The laminated glazing as claimed in claim 1, wherein the pressure-sensitive adhesive is chosen from pressure-sensitive adhesives based on acrylates and pressure-sensitive adhesives based on silicone.
 6. The laminated glazing as claimed in claim 1, wherein the heat-sensitive functional sheet is based on encapsulated liquid crystals, on electrophoretic particles dispersed in a medium, on particles dispersed in an electrophoretic fluid or on particles for the polarization of light.
 7. The laminated glazing as claimed in claim 1, wherein the solar-protection sheet is made of silver or any other metal having light-reflecting properties or a metal or metal compound having light-absorbing properties.
 8. The laminated glazing as claimed in claim 1, wherein the laminated glazing is flat or bent.
 9. The laminated glazing as claimed in claim 1, wherein the laminated glazing is a vehicle glazing chosen from a windshield, a front side glazing, a rear side glazing, a rear window and a roof glazing.
 10. The laminated glazing as claimed in claim 1, wherein the laminated glazing is a glazing of a vehicle chosen from a motor vehicle, a train, a truck, a plane and a bus.
 11. A process for the manufacture of a laminated glazing as claimed in claim 1, comprising stages of installing the different sheets, wherein the stages take place starting (i) from the installing of the interlayer sheet made of thermoplastic polymer on the internal face of the first glass sheet, or starting (ii) from the installing of the sheet of pressure-sensitive adhesive on the internal face of the second glass sheet or starting (iii) from the installing of the sheet of pressure-sensitive adhesive on at least one of the two faces of the heat-sensitive functional sheet.
 12. The process for the manufacture of a laminated glazing as claimed in claim 11, comprising: at least one stage of installing the interlayer sheet made of thermoplastic polymer on the internal face of the first glass sheet, optionally bent beforehand, and optionally the installation of solar-protection sheet on the face which has remained vacant of said interlayer sheet, which is thus sandwiched between said first glass sheet and said optional solar-protection sheet, so as to form a first partial laminate, and/or at least one stage of installing a first and/or a second sheet of pressure-sensitive adhesive on at least one of the two faces of a heat-sensitive functional sheet.
 13. The process as claimed in claim 11, wherein the first sheet of pressure-sensitive adhesive (5) is positioned on the first face of the heat-sensitive functional sheet and the second sheet of pressure-sensitive adhesive is positioned on the second face of said heat-sensitive functional sheet, which has remained vacant, so as to obtain a second partial laminate.
 14. The process as claimed in claim 13, wherein the second partial laminate is applied via one of its faces which are pressure-sensitive adhesives on or under the first partial laminate, either directly on the vacant face of the sheet of thermoplastic polymer of the latter or optionally on the vacant face of the solar-protection sheet, when the latter is present, of the first partial laminate, and the second glass sheet, optionally bent beforehand, is applied at its internal face on or under the face of the resulting laminate, opposite the face which has remained vacant of the first glass sheet.
 15. The process as claimed in claim 13, wherein the second glass sheet, optionally bent beforehand, is applied at its interior face on or under one of the faces of said second partial laminate, so as to form a third partial laminate.
 16. The process as claimed in claim 15, wherein said third partial laminate is installed via its face which is a pressure-sensitive adhesive on or under the first partial laminate, either directly on the vacant face of its sheet of thermoplastic polymer or optionally on the vacant face of its solar-protection sheet, when the latter is present.
 17. The process for the manufacture of a laminated glazing as claimed in claim 11, additionally comprising: a stage of degassing the resulting laminate under vacuum, with use of a peripheral seal or of a vacuum bag, optionally a stage of heat sealing of the edges of said laminate, and an autoclaving stage.
 18. The process for the manufacture of a laminated glazing as claimed in claim 11, additionally comprising at least one calendering stage, optionally a hot calendering stage.
 19. A method comprising manufacturing a vehicle glazing chosen from a windshield, a front side glazing, a rear side glazing, a rear window and a roof glazing and/or manufacturing a glazing for a vehicle chosen from a motor vehicle, a train, a truck, an aircraft and a bus, with a laminated glazing as claimed in claim
 1. 